The representation of the visual field on the sub-cortical centers of the cat and rabbit

In the visual system the primary problem has been the identification of the visual pathway - the fiber systems along which the impulses arising in the eyes pass to the various subcortical levels and finally to the cortex - their precise localization, boundaries, and the extent of the terminal areas of the pathway. The second problem has been to determine whether, and to what extent, the original spatial and dimensional relationships present in visual space and in the retina are preserved in the pathways and centers, and if they are, how and where the various distinct areas of the retina, i.e. the fovea, the extra-foveal peripheral quadrants, the horizontal and vertical meridians, were represented in the various levels of the visual pathway

Affectivity of Chemical Weed Control in Commercial Tea Plantations: A Case Study in Hapugastenne Estate, Maskeliya, Sri Lanka

AbstractThe usage of agro chemicals on food crops is getting restricted day by day with the sanctions set by the institutes devoted in food security, mainly due to the disclosure of their harmful residual effects on human health. Thus, several Commercial Tea Plantation companies have voluntarily suspended the use of many Herbicides on Tea under their charge, which are still permitted to use in Sri Lanka. Intense emergence of Herbicide tolerant weed species on treated areas was noted in the mean time, although this crucial factor had been remained un-noticed as a result of frequent manual weeding under taken by the Tea estates under various other accounts such as plucking, fertilizer application, mossing and ferning green manure etc. Therefore, an investigation was carried out to ascertain the affectivity of Herbicides recommended for Commercial Tea Plantations, over a period of 24 months in Hapugastenne Tea Garden, Maskeliya, since year 2012 at five different elevations, with five replicates set at each elevation. Results show that over 20 weed species out of 23 acutely problematic weeds which cause great damage to Tea crop, are entirely tolerant to Diurone, Paraquat and Glyphosate and cannot be controlled by using said Herbicides. It was further revealed that such weed species have the ability to turn a Tea Plantation into a totally unproductive and economically non-viable unit within a time period of one to two years depending on the herbicide tolerant weed species present. These weeds are capable of suppressing the growth of the Tea bushes by making them stunted in growth with poor bush frames, turn the foliage yellowish and induce defoliation, unless they were removed completely by manual uprooting

Combining xenoestrogens at levels below individual no-observed-effect concentrations dramatically enhances steroid hormone action.

The low potency of many man-made estrogenic chemicals, so-called xenoestrogens, has been used to suggest that risks arising from exposure to individual chemicals are negligible. Another argument used to dismiss concerns of health effects is that endogenous steroidal estrogens are too potent for xenoestrogens to contribute significantly to estrogenic effects. Using a yeast reporter gene assay with the human estrogen receptoralpha, we tested these ideas experimentally by assessing the ability of a combination of 11 xenoestrogens to affect the actions of 17ss-estradiol. Significantly, each xenoestrogen was present at a level well below its no-observed-effect concentration (NOEC). To derive accurate descriptions of low effects, we recorded concentration-response relationships for each xenoestrogen and for 17ss-estradiol. We used these data to predict entire concentration-response curves of mixtures of xenoestrogens with 17ss-estradiol, assuming additive combination effects. Over a large range of concentrations, the experimentally observed responses decisively confirmed the model predictions. The combined additive effect of the 11 xenoestrogens led to a dramatic enhancement of the hormone's action, even when each single agent was present below its NOEC. Our results show that not even sub-NOEC levels of xenoestrogens can be considered to be without effect on potent steroidal estrogens when they act in concert with a large number of similarly acting chemicals. It remains to be seen to what degree these effects can be neutralized by environmental chemicals with antiestrogenic activity. Nevertheless, potential human and wildlife responses induced by additive combination effects of xenoestrogens deserve serious consideration

Mechanisms of Mitochondrial DNA Deletion Formation.

Mitochondrial DNA (mtDNA) encodes a subset of genes which are essential for oxidative phosphorylation. Deletions in the mtDNA can ablate a number of these genes and result in mitochondrial dysfunction, which is associated with bona fide mitochondrial disorders. Although mtDNA deletions are thought to occur as a result of replication errors or following double-strand breaks, the exact mechanism(s) behind deletion formation have yet to be determined. In this review we discuss the current knowledge about the fate of mtDNA following double-strand breaks, including the molecular players which mediate the degradation of linear mtDNA fragments and possible mechanisms of recircularization. We propose that mtDNA deletions formed from replication errors versus following double-strand breaks can be mediated by separate pathways.We are grateful for support from the National Institutes of Health Grants 1R01AG036871, 5R01EY010804, and 1R01NS079965, the Muscular Dystrophy Association and the Champ Foundation (to C.T.M.); and the Medical Research Council Grant MC_UU_00015/4 (to M.M.)

State College Times, May 9, 1933

Volume 21, Issue 106https://scholarworks.sjsu.edu/spartan_daily_1933/1060/thumbnail.jp

Charge regulation in lipid membranes due to lipid mobility

Lipid bilayer membranes are ubiquitous in biology and electrostatics play a key role in their functionality. The interfacial electrostatics of lipid bilayers involves interplay between the surface potential and charge regulation in the form of ion binding, protonation and lipid mobility. Mobile lipid charge regulation in particular is unique to lipid interfaces and is thought to be an important factor in charged macromolecule-membrane interactions. We used Atomic Force Microscopy (AFM) for the first nanometer scale experimental demonstration of mobile lipid charge regulation occurring in supported lipid bilayer membranes. By combining finite element computer simulations and experimental AFM data, we showed that mobile lipid charge regulation accounts for the short range deviations from the expected electrostatics over anionic lipids. We also accounted for van der Waal interactions and electrolyte ion binding in our calculations and found the mobility of the lipid to be the dominant factor in the short range deviations. Control experiments on silicon nitride surfaces, whose surface charges are immobile, showed that the short range deviation could be accounted for by the formation of a stem layer due to cation binding. Further evidence for tip-induced mobile lipid charge regulation was presented in the form of clear differences in the short range electrostatics of mobile fluid phase lipids when compared to immobile gel phase lipids. Furthermore, our data confirmed the theoretically predicted differences between surfaces containing mobile versus immobile charges

Oil palm industry in Sri Lanka: Its production potential and current status, and future prospects

No abstract availabl

CHANGES IN VEGETATION AND SOIL CHARACTERISTICS OF REGENERATING FOREST AT RANDENIGALA

Victoria, Randenigala, Rantambe(VRR) sanctuary is the largest sanctuary in Sri Lanka. Certainareas in the Rantambe catchment was disturbed for the construction of Randenigala dam in 1987with no planned rehabilitation programme. This study was initiated to assess the changingpattern of vegetation and its influence on soil physical and chemical properties of disturbedforestland near Randenigala dam, relative to the surrc:unding undisturbed natural forest.The site was located 1 km North of the Randenigala Dam in a hilly slope in the intermediatezone and was surrounded by relatively undisturbed natural vegetation of dry mixed evergreenforest. In the sampling site (about 100 ha) the vegetation and soil has been removed down toparental material for dam construction. Three rectangular transacts measuring 5mxlOOmweremarked in each natural and regenerating forest sites .AlI plants were identified, height anddiameter at breast height (dbh) over >2cm of woody plants were measured. Soil pits were cut inboth disturbed and undisturbed forest sites and profiles were described. Soil samples wereremoved from each horizons for the analysis of soil physical and chemical properties. In thedegraded sites, soil pits were cut in the open area (6m), in the canopy edge (3m), and 0.5m fromthe tree base of dominant pioneer tree species to observe the soil improvement.Plant density of the undisturbed forest was three times higher than the disturbed forest andconsists of 17 trees, six shrubs, and four woody climber species. Five trees, six shrubs, onewoody climber, two grasses, and three creepy herbaceous species were found in the regeneratingforest. Common families present were Euphorbiaceae (38%), Sterculaceae (24%) and Rubaceae(12%) in the undisturbed forest and Hipocraraceae (40%), Leguminosae (26%) andApocynaceae (18%)in the disturbed forest.Five and two major soil horizons were identified in the undisturbed and disturbed forest sites,respectively. Soil N, P, K and organic matter contents and hydraulic conductivity were greaterand the bulk density was lower in the undisturbed site. The mean weight diameter (MWD) of thesoil aggregate was greater in the soil horizons of undisturbed site (1.6-2.7mm) compared to thedegraded site (1.1 mm). Similar trends were also observed for wet aggregate stability in theundisturbed (90% remaining) and disturbed (71% remaining) in forest soils. However, MWD(1.5mm) and wet aggregate stability (83% remaining) gradually improved towards the tree baseof pioneer tree species. (i.e. under Bouhinia racemosat in the regenerating disturbed forest site.Increase in soil organic matter content stabilizes the soil aggregates and makes soil moreresistant to erosion by wind and water under the canopy of pioneer species. The retention of soilunder these trees contributes to the development of the soil profile, improvement of soil fertilityand subsequently, the vegetation diversity of degraded sites.

Growth and elemental accumulation by canola on soil amended with coal fly ash

To explore the agronomic potential of an Australian coal fly ash, we conducted two glasshouse experiments in which we measured chlorophyll fluorescence, CO2 assimilation (A), transpiration, stomacal conductance, biomass accumulation, seed yield, and elemental uptake for canola (Brassica napus) grown on soil amended with an alkaline fly ash. In Experiment 1, application of up to 25 Mg/ha of fly ash increased A and plant weight early in the season before flowering and seed yield by up to 21%. However, at larger rates of ash application A, plant growth, chlorophyll concentration, and yield were all reduced. Increases in early vigor and seed yield were associated with enhanced uptake of phosphorus (P) by the plants treated with fly ash. Fly ash application did not influence accumulation of B, Cu, Mo, or Zn in the stems at any stage of plant growth or in the seed at harvest, except Mo concentration, which was elevated in the seed. Accumulation of these elements was mostly in the leaves, where concentrations of Cu and Mo increased with any amount of ash applied while that of B occurred only with ash applied at 625 Mg/ha. In Experiment 2, fly ash applied at 500 Mg/ha and mixed into die whole 30 cm soil core was detrimental to growth and yield of canola, compared with restricting mixing to 5 or 15 cm depth. In contrast, application of ash at 250 Mg/ha with increasing depth of mixing increased A and seed yield. We concluded that fly ash applied at not more than 25 Mg/ha and mixed into the top 10 to 15 cm of soil is sufficient to obtain yield benefits. Copyright © 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved